Cellulose resin, molding material, molded body, and method for producing cellulose resin

ABSTRACT

A cellulose resin wherein a hydrogen atom of a hydroxy group of cellulose is substituted with a long-chain component which is a linear saturated aliphatic acyl group having 14 or more carbon atoms and a short-chain component which is an acyl group (propionyl group) having 3 carbon atoms, the degree of substitution with the long-chain component (DS Lo ) and the degree of substitution with the short-chain component (DS Sh ) satisfy the following conditional expressions (1) and (2):
 
 DS   Lo   +DS   Sh ≥2.1  (1)
 
4≤ DS   Sh   /DS   Lo ≤12  (2),
 
the Izod impact strength is 5.0 kJ/m 2  or more, and the MFR (melt flow rate at 200° C. and under a load of 5 kg) is 10 g/10 min or more.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No.PCT/JP2018/020987 filed May 31, 2018, claiming priority based onJapanese Patent Application No. 2017-109250 filed Jun. 1, 2017 andJapanese Patent Application No. 2018-059565 filed Mar. 27, 2018, theentire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a cellulose resin, a molding material,a molded body, and a method for producing the cellulose resin.

BACKGROUND ART

Bioplastics made from vegetable law materials can contribute tocountermeasures against petroleum depletion and global warming, and hasbeen started being used in jeneral products such as packaging,containers and fibers but also in durable products such as electronicequipment and automobiles.

However, conventional bioplastics, such as polylactic acid,polyhydroxyalkanates, modified starch, are all made of starch-basedmaterials, i.e., edible parts. Therefore, in view of concerns about foodshortages in the future, the development of new bioplastics usingnon-edible parts as raw materials is required.

As a raw material of the non-edible part, cellulose, which is a maincomponent of wood and vegetation, is typical, and various bioplasticsusing the cellulose have been developed and commercialized.

However, the process of chemically modifying cellulose into a resinsuitable for molding is complicated and labor-intensive, and theproduction energy is high, so that the production cost of celluloseresin is high. Furthermore, the mechanical characteristics of the resinsproduced are not sufficient.

Cellulose is produced as pulp by chemically separating lignin andhemicellulose from wood or the like, with the help of a chemical agent.Alternatively, since cotton is almost made of cellulose, it can be usedas it is. Such a cellulose, which is a polymer formed by polymerizationof β-glucose, has a strong intermolecular force due to hydrogen bondsbecause it has many hydroxy groups. Therefore, it is hard and brittle,does not have thermoplasticity, and is low in solvent solubility exceptfor a special solvent.

Various studies have been conducted to modify such a cellulose.

As a method of modifying cellulose, a method of replacing a hydrogenatom of a hydroxy group of cellulose with a short-chain acyl group suchas an acetyl group is known. According to this method, since the numberof hydroxy groups can be reduced, the intermolecular force of cellulosecan be reduced. Furthermore, it has been investigated to introduce along-chain organic group having a higher carbon number in addition to ashort-chain acyl group such as an acetyl group to produce a cellulosederivative having a good thermoplastic property.

For example, Patent Literature 1 describes a cellulose acylate filmproduced from a solution obtained by dissolving a cellulose acylate inwhich the substitution degree of hydroxy groups of the cellulosesatisfies predetermined conditions, and a polycarboxylic acid which has22 or less carbon atoms and a carboxyl group having an acid dissociationindex of 4.4 or less, in an organic solvent. The literature describes acase where cellulose triacetate was used as the cellulose acylate. Sincesuch a film can be easily removed from a support after producing bycasting and drying, the productivity thereof is excellent.

Additionally, Patent Literature 2 describes a cellulose derivativeproduced by substituting at least a part of hydrogen atoms of hydroxygroups of a cellulose with a short-chain acyl group (for example, analiphatic acyl group having 2 to 4 carbon atoms) and a long-chain acylgroup (for example, an aliphatic acyl group having 5 to 20 carbonatoms), and that the cellulose derivative has satisfactorythermoplasticity, strength and fracture elongation and is suitable formolding process.

Patent Literature 3 describes a process for producing a cellulosederivative, including the steps of introducing a long-chain organicgroup having 5 or more carbon atoms and a short-chain organic grouphaving 4 or less carbon atoms to a cellulose by reacting them in asolid-liquid heterogeneous system, and conducting solid-liquidseparation to obtain the cellulose derivative.

Patent Literature 4 describes a cellulose derivative having cardanolintroduced therein, and that the cellulose derivative was improved inthermoplasticity, and mechanical characteristics.

Patent Literature 5 describes a cellulose derivative having cardanol andabietic acid introduced therein, and that the cellulose derivative wasimproved in thermoplasticity, and mechanical characteristics.

Patent Literature 6 describes a process for producing a cellulosederivative including a first step of reacting a cellulose with along-chain reactant for introducing a long-chain organic group having 5or more carbon atoms in a solid-liquid heterogeneous system to form acellulose derivative having the long-chain organic group introducedtherein and remaining hydroxy groups which are a part of the hydroxygroups of the cellulose, in a swollen state, and performing solid-liquidseparation to obtain an intermediate cellulose derivative; and a secondstep of reacting the intermediate cellulose derivative with ashort-chain reactant for introducing a short-chain organic group having4 or less carbon atoms to form a final cellulose derivative having theshort-chain organic group introduced therein.

Patent Document 7 describes a cellulose derivative in which a long-chainorganic group having 5 or more carbon atoms and a short-chain organicgroup having 4 or less carbon atoms are introduced by utilizing ahydroxy group of cellulose, the cellulose derivative has a crystalstructure derived from a cellulose derivative portion to which theshort-chain organic group is bonded, and the average number of hydroxygroups per glucose unit is 1.0 or less.

CITATION LIST Patent Literature

Patent Literature 1: JP2002-265639A

Patent Literature 2: JP2010-121121A

Patent Literature 3: WO2013/180278

Patent Literature 4: WO2011/043279

Patent Literature 5: WO2011/043280

Patent Literature 6: WO2015/060122

Patent Literature 7: WO2016/067662

SUMMARY OF INVENTION Technical Problem

An object of the present invention is to provide a cellulose resinhaving excellent mechanical characteristics and thermoplasticity, and amethod for producing the cellulose resin.

Solution to Problem

According to an aspect of the present invention, there is provided acellulose resin formed by substituting hydrogen atoms of hydroxy groupsof a cellulose with a long-chain component being a linear saturatedaliphatic acyl group having 14 or more carbon atoms and a short-chaincomponent being an acyl group (propionyl group) having 3 carbon atoms,

wherein a degree of substitution with the long-chain component (DS_(Lo))and a degree of substitution with the short-chain component (DS_(Sh))satisfy the following conditional expressions (1) and (2):DS _(Lo) +DS _(Sh)≥2.1  (1)4≤DS _(Sh) /DS _(Lo)≤12  (2),

Izod impact strength is 5.0 kJ/m² or more, and

an MFR (melt flow rate at 200□ and under a load of 5 kg) is 10 g/10 minor more.

According to another aspect of the present invention, there is provideda molding material comprising the above-mentioned cellulose resin.

According to another aspect of the present invention, there is provideda molded body formed by using the above-mentioned molding material.

According to another aspect of the present invention, there is provideda method for producing the cellulose resin according to any one ofclaims 1 to 4, comprising:

acylating hydroxy groups of a cellulose constituting a pulp by reacting

-   -   the pulp having a polymerization degree of 300 to 700 and        dispersed in an organic solvent with    -   propionyl chloride, and    -   a long-chain reactant being an acid chloride of a long-chain        fatty acid and comprising the long-chain component,    -   in the presence of the acid trapping component and under        warming; and separating an acylated cellulose obtained in the        acylating from the organic solvent.

Advantageous Effects of Invention

According to an exemplary embodiment of the present invention, acellulose resin having excellent mechanical characteristics andthermoplasticity and a method for producing the cellulose resin can beprovided.

DESCRIPTION OF EMBODIMENTS

A cellulose resin according to an exemplary embodiment of the presentinvention is a cellulose derivative formed by substituting hydrogenatoms of hydroxy groups of a cellulose with a long-chain component whichis a linear saturated aliphatic acyl group having 14 or more carbonatoms and a short-chain component which is an acyl group having 3 carbonatoms (propionyl group).

It is preferable that the degree of substitution with the long-chaincomponent (DS_(Lo)) and the degree of substitution with the short-chaincomponent (DS_(Sh)) satisfy the following conditional expressions (1)and (2):DS _(Lo) +DS _(Sh)≥2.1  (1)4≤DS _(Sh) /DS _(Lo)≤12  (2)

The DS_(Lo)+DS_(Sh) preferably in the range of 2.1 to 2.6. The DS_(Lo)is particularly preferably in the range of 0.3 to 0.5, and morepreferably in the range of 0.35 to 0.45. The DS_(Sh) is particularlypreferably in the range of 1.9 to 2.3, and more preferably in the rangeof 1.9 to 2.2.

In the cellulose resin according to the exemplary embodiment of thepresent invention, it is preferable that the long-chain component andthe short-chain component are introduced into a cellulose having adegree of polymerization (DP) in the range of 300 to 700 by using ahydroxy group of the cellulose. The degree of polymerization (DP) of thecellulose (prior to the introduction of the long-chain component and theshort-chain component) was calculated by measuring the limitingviscosity [η] in accordance with the JIS P8215 and calculating thelimiting viscosity according to the following equation.[η]=1.67×DP ^(0.71)

Such a cellulose resin can have excellent mechanical characteristics andthermoplasticity. As mechanical characteristics, for example, acellulose resin having excellent impact resistance can be obtained.

By introducing the long-chain component, thermoplasticity and waterresistance can be enhanced, and by having the long-chain component andthe short-chain component in a specific ratio, mechanicalcharacteristics such as bending strength, elastic modulus and impactresistance can be enhanced. The carbon number of the long-chaincomponent is particularly preferably in the range of 16 to 20.

In the cellulose-based resin according to an exemplary embodiment of thepresent invention, from the viewpoints of flowability, water resistance,impact resistance, and the like, it is preferable that the averagenumber of hydroxyl groups per glucose unit (hydroxy group remainingdegree, DS_(OH)) is 0.9 or less.

The cellulose resin according to an exemplary embodiment of the presentinvention preferably has an Izod impact strength of 5.0 kJ/m² or more,and an MFR (melt flow rate at 200° C. and under a load of 5 kg) of 10g/10 min or more. The Izod impact strength is a notched Izod impactstrength measured according to JIS K7110. The MFR is preferably 10 g/10min or more, more preferably 30 g/10 min or more, and more preferably 50g/10 min or more from the viewpoint of preventing the flowability frombecoming too low and hindering molding. The upper limit of the MFR isnot particularly limited, but generally can be set to 200 g/10 min orless, set to 180 g/10 min or less, and set to 150 g/10 min or less. Whenthe MFR is too large, the molecular weight of the resin tends to be low,and accordingly, the impact resistance tends to be low.

In a method for producing a cellulose resin according to an exemplaryembodiment of the present invention, it is preferable that the organicsolvent is a solvent providing a liquid holding rate by the cellulose of90% by volume or more. The acid trapping component preferably includestriethylamine or pyridine. The reaction temperature of the acylationstep is preferably 50 to 100° C. The amount of the organic solvent ispreferably 10 to 50 times as large as the dry mass of the pulp. Inaddition, the method may further include, after the above acylationstep, a step of adding an alkaline aqueous solution and maintaining at25 to 75° C. for 1 to 5 hours.

(Cellulose)

Cellulose is a straight-chain polymer obtained by polymerizingβ-D-glucose (β-D-glucopyranose) molecules represented by the followingformula (1) via β (1→4) glycoside bond. Each of glucose unitsconstituting cellulose has three hydroxy groups (where n represents anatural number). In the exemplary embodiment, using these hydroxygroups, the short-chain organic group and long-chain organic group canbe introduced into the cellulose.

Cellulose is a main component of plants and can be obtained by aseparation treatment for removing other components such as lignin fromplants. Other than those thus obtained, cotton (for example, cottonlinters) having a high cellulose content and pulp (for example, woodpulp) can be used directly or after they are purified. As the shape,size and form of the cellulose or a derivative thereof to be used as araw material, a powder form cellulose or a derivative thereof having anappropriate particle size and particle shape is preferably used in viewof reactivity, solid-liquid separation and handling. For example, afibrous or powdery cellulose or a derivative thereof having a diameterof 1 to 100 μm (preferably 10 to 50 μm) and a length of 10 μm to 100 mm(preferably 100 μm to 10 mm) can be used.

The polymerization degree of cellulose is preferably in the range of 300to 700, more preferably 350 to 650, and still more preferably 400 to600, as the degree of glucose polymerization (average degree ofpolymerization). If the polymerization degree is too low, the impactresistance of the produced resin may not be sufficient in some cases.Conversely, if the polymerization degree is too high, the flowability ofthe produced resin becomes too low, interfering with molding in somecases.

Cellulose may be mixed with a similar structure material such as chitin,chitosan, hemicellulose, xylan, glucomannan, curdlan, and the like. Whencellulose is mixed with the similar structure material, the amount ofthe material relative to the total amount of mixture is preferably 30%by mass or less preferably 20% by mass or less and further preferably10% by mass or less.

The description in the above is directed to cellulose; however, thepresent invention is applicable to analogs of the cellulose, such asgeneral non-edible polysaccharides, i.e., chitin, chitosan,hemicellulose, xylan, glucomannan and curdlan.

(Long-Chain Component)

The cellulose resin according to an exemplary embodiment of the presentinvention is a resin formed by introducing a long-chain component asmentioned above in addition to a short-chain component as mentionedabove by use of a hydroxy group of a cellulose.

Such a long-chain component can be introduced by reacting a hydroxygroup of a cellulose with a long-chain reactant. The long-chaincomponent corresponds to an acyl group introduced in place of thehydrogen atom of a hydroxy group of a cellulose. A long-chain organicgroup of the long-chain component and a pyranose ring of a cellulose canbe bound via an ester bond. The acyl group introduced is a linearsaturated aliphatic acyl group having 14 or more carbon atoms. A linearsaturated aliphatic acyl group having 14 to 30 carbon atoms ismentioned; a linear saturated aliphatic acyl group having 14 to 22carbon atoms is preferable; and groups (tetradecanoyl group,hexadecanoyl group, octadecanoyl group, icosanoyl group, docosanoylgroup) obtained by removing OH from a carboxyl group of myristic acid,palmitic acid, stearic acid, arachidic acid and behenic acid, are morepreferable.

The long-chain reactant is a compound having at least one functionalgroup capable of reacting with a hydroxy group of a cellulose; forexample, a compound having a carboxyl group, a carboxylic acid halidegroup or a carboxylic acid anhydride group can be used.

As the long-chain reactant, for example, a long-chain carboxylic acidhaving 14 or more carbon atoms and an acid halide or acid anhydride ofthe long-chain carboxylic acid can be used. The saturation degrees ofthese carboxylic acids or carboxylic acid derivatives are desirably ashigh as possible; a linear saturated fatty acid, an acid halide oranhydride thereof is preferable. Examples of the long-chain carboxylicacid include linear saturated fatty acids such as myristic acid,pentadecylic acid, palmitic acid, margaric acid, stearic acid, arachidicacid, behenic acid, lignoceric acid, cerotic acid, montanic acid andmelissic acid. Myristic acid, palmitic acid, stearic acid, arachidicacid and behenic acid are preferable. Further as the long-chaincarboxylic acid, a carboxylic acid obtained from natural products ispreferable, in view of environmental harmony.

The long-chain component has preferably 14 or more carbon atoms andparticularly preferably 16 or more carbon atoms. In view of reactionefficiency in introducing a long-chain component, the long-chaincomponent has preferably 48 or less carbon atoms, more preferably 36 orless carbon atoms and particularly preferably 24 or less carbon atoms. Asingle type of a long-chain component may be contained alone, or twotypes or more of long-chain components may be contained.

The average number of long-chain components introduced per glucose unitof a cellulose (DS_(LO)) (long-chain component introduction ratio), inother words, the average number of hydroxy groups substituted with along-chain component (a linear saturated aliphatic acyl group having 14or more carbon atoms) per glucose unit (hydroxy group substitutiondegree), preferably satisfy the conditions represented by the aboveexpressions (1) and (2). DS_(LO) can be set to fall within the range of,for example, 0.2 to 0.6, in accordance with the structure andintroduction amount of a short-chain component, the structure of along-chain component, physical properties required for a desired productand the production efficiency. In order to obtain a more sufficientintroduction effect of a long-chain component, DS_(LO) is preferably 0.2or more, more preferably 0.3 or more and further preferably 0.35 ormore. In view of production efficiency and durability (e.g., strength,heat resistance), DS_(L0) is preferably 0.6 or less, more preferably 0.5or less and further preferably 0.45 or less.

The properties of a cellulose or a derivative thereof can be improved byintroducing a long-chain component as mentioned above into the celluloseor a derivative thereof. More specifically, water resistance,thermoplasticity and mechanical characteristics can be improved.

(Short-Chain Component)

The cellulose resin according to an exemplary embodiment of the presentinvention is a resin formed by introducing a short-chain component asmentioned above in addition to a long-chain component as mentionedabove, using hydroxy groups of a cellulose. As the short-chaincomponent, a propionyl group is preferable.

Such a short-chain component can be introduced by reacting a hydroxygroup of a cellulose with a short-chain reactant. The short-chaincomponent corresponds to an acyl group moiety introduced in place of ahydrogen atom of a hydroxy group of the cellulose. The short-chainorganic group (propyl group) of a short-chain component and the pyranosering of the cellulose can be bound via an ester bond.

The short-chain reactant is a compound having at least one functionalgroup capable of reacting with a hydroxy group of a cellulose. Examplesthereof include compounds having a carboxyl group, a carboxylic acidhalide group and a carboxylic acid anhydride group. Specific examplesthereof include an aliphatic monocarboxylic acid, an acid halide or acidanhydride thereof.

It is more preferable that the short-chain component has 3 carbon atoms,and the hydrogen atom of a hydroxy group of the cellulose is replacedwith an acyl group (propionyl group) having 3 carbon atoms.

The average number of short-chain components introduced per glucose unitof a cellulose (DS_(Sh)) (short-chain component introduction ratio), inother words, the average number of hydroxy groups substituted with ashort-chain component (propionyl group) per glucose unit (thesubstitution degree of hydroxy groups), preferably satisfy theconditions represented by the above expressions (1) and (2) (note that,3≥DS_(Lo)+DS_(Sh)). DS_(Sh) can be set to fall within the range of 1.7to 2.8. In order to obtain a more sufficient effect of introducing ashort-chain component, DS_(Sh) is preferably 1.7 or more. Particularly,in view of, e.g., water resistance and flowability, DS_(Sh) ispreferably 1.9 or more and more preferably 2.0. In order to obtain thesufficient effect of a long-chain component in addition to the effect ofintroducing a short-chain component, DS_(Sh) is preferably 2.6 or less,more preferably 2.3 or less and further preferably 2.2 or less.

By introducing the aforementioned short-chain component into a celluloseor a derivative thereof, the intermolecular force (intermolecular bond)of the cellulose can be reduced; and mechanical characteristics such aselastic modulus, chemical resistance and physical properties such assurface hardness can be enhanced.

The ratio (DS_(Sh)/DS_(Lo)) of the introduction ratio of the long-chaincomponent to the introduction ratio of the short-chain component ispreferably 4 or more and 12 or less. If the ratio is less than 4, thematerial tends to become too flexible and accordingly its strength andheat resistance tend to decrease. On the contrary, if the ratio exceeds12, thermoplasticity becomes insufficient, with the result that itbecomes unsuitable for molding applications. In these respects,DS_(Sh)/DS_(Lo) is more preferably 4.5 or more, more preferably 10 orless, and still more preferably 7.5 or less.

The sum of the ratio of the long-chain component and the ratio of theshort-chain component (DS_(Lo)+DS_(Sh)) is preferably 2.1 or more, morepreferably 2.2 or more, more preferably 2.25 or more, from the viewpointof obtaining adequate introduction effects of the long-chain componentand the short-chain component, and more preferably 2.6 or less, morepreferably 2.55 or less, from the viewpoint of mechanicalcharacteristics and the like.

(Residual Amount of Hydroxy Groups in Cellulose Resin)

As the residual amount of hydroxy groups increases, the maximum strengthand heat resistance of the cellulose resin tend to increase; whereaswater absorbability tends to increase. In contrast, as the conversionrate (degree of substitution) of hydroxy groups increases, waterabsorbability tends to decrease, plasticity and breaking strain tend toincrease; whereas, maximum strength and heat resistance tend todecrease. In consideration of these tendencies etc., the conversion rateof hydroxy groups can be appropriately set.

The average number of the remaining hydroxy group per glucose unit(hydroxy group remaining degree, DS_(OH)) of a final cellulose resin canbe set to fall within the range of 0 to 0.9 (note that,DS_(Lo)+DS_(Sh)+DS_(OH)=3). If DS_(Lo)+DS_(Sh) is in the range of 2.1 to2.6, DS_(OH) can be set in the range of 0.4 to 0.9. In view ofmechanical characteristics such as maximum strength and durability suchas heat resistance, a hydroxy group may remain. For example, the hydroxygroup remaining degree can be set at 0.01 or more and further 0.1 ormore. Particularly, in view of flowability, the hydroxy group remainingdegree of a final cellulose resin is preferably 0.1 or more and morepreferably 0.2 or more. In view of, e.g., water resistance in additionto flowability, the hydroxy group remaining degree is preferably 0.9 orless. Further in view of, e.g., impact resistance, the hydroxy groupremaining degree is preferably 0.6 or less and more preferably 0.5 orless.

(Activation of Cellulose)

Before the reaction step for introducing a long-chain component and ashort-chain component into a cellulose, an activation treatment(pretreatment step) can be performed in order to increase the reactivityof the cellulose. As the activation treatment, an activation treatmentwhich is routinely performed before acetylation of a cellulose can beapplied.

In the activation treatment, a cellulose is swollen by bringing thecellulose into contact with a solvent, for example, by a method ofspraying an activation solvent having affinity for a cellulose to thecellulose or by a method (soaking method) of soaking a cellulose in anactivation solvent. Owing to the treatment, a reactant easily penetratesbetween cellulose molecular chains (if a solvent and a catalyst areused, a reactant easily penetrates together with these), with the resultthat the reactivity of the cellulose improves. Herein, examples of theactivation solvent include water; carboxylic acids such as acetic acid,propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid,caprylic acid, pelargonic acid and stearic acid; alcohols such asmethanol, ethanol, propanol and isopropanol; nitrogen-containingcompounds such as dimethylformamide, formamide, ethanolamine andpyridine; and sulfoxide compounds such as dimethylsulfoxide. These canbe used in combination of two or more types. Particularly preferably,water, acetic acid, pyridine and dimethylsulfoxide can be used.

A cellulose can be activated by putting it in a long-chain fatty acid.If the melting point of the long-chain fatty acid is room temperature ormore, a cellulose can be heated up to the melting point or more.

The use amount of activation solvent relative to a cellulose (100 partsby mass) can be set to be, for example, 10 parts by mass or more,preferably 20 parts by mass or more and more preferably 30 parts by massor more. If a cellulose is soaked in an activation solvent, the useamount of activation solvent relative to the cellulose in term of mass,can be set to be, for example, the same or more, preferably 5 times ormore and more preferably 10 times or more. In view of load for removingan activation solvent after the pretreatment and cost reduction ofmaterials, the use amount of activation solvent is preferably 300 timesor less, more preferably 100 times or less and further preferably 50times or less.

The temperature of the activation treatment can be appropriately setwithin the range of, for example, 0 to 100° C. In view of the efficiencyof activation and reduction of energy cost, the temperature ispreferably 10 to 40° C. and more preferably 15 to 35° C.

When a cellulose is put in a melted long-chain fatty acid, the cellulosecan be heated up to melting point or more of the long-chain fatty acid.

The time for the activation treatment can be appropriately set withinthe range of, for example, 0.1 hour to 72 hours. In order to performsufficient activation and reduce the treatment time, the time ispreferably 0.1 hour to 24 hours and more preferably 0.5 hours to 3hours.

After the activation treatment, an excessive activation solvent can beremoved by a solid-liquid separation method such as suction filtration,filter press and compression.

The activation solvent contained in a cellulose can be substituted withthe solvent to be used in the reaction after the activation treatment.For example, a substitution treatment can be performed in accordancewith the soaking method for an activation treatment mentioned above bychanging the activation solvent to the solvent to be used in thereaction.

(Method for Introducing Long-Chain Component and Short-Chain Component)

A cellulose derivative (cellulose resin) according to an exemplaryembodiment can be produced in accordance with the method shown below.

A process for producing a cellulose derivative according to an exemplaryembodiment includes a step of acylating hydroxy groups of a celluloseconstituting pulp by reacting, in an organic solvent, the pulp dispersedin the organic solvent, a short-chain reactant (short-chain acylatingagent) and a long-chain reactant (long-chain acylating agent) in thepresence of an acid trapping component while warming. It is preferablethat the short-chain reactant (short-chain acylating agent) and thelong-chain reactant (long-chain acylating agent) are dissolved in thesolvent. The acid trapping component may be also used as a solvent.

As a long-chain reactant for introducing a long-chain component in acellulose, an acid chloride of a linear saturated fatty acid asmentioned above is preferable. A single type of a long-chain reactantmay be used alone or two types or more of long-chain reactants may beused in combination. As a short-chain reactant for introducing ashort-chain component in a cellulose, propionyl chloride is preferable.

The addition amounts of the long-chain reactant and short-chain reactantcan be set in accordance with the degree of substitution (DS_(Lo)) witha long-chain component and the degree of substitution (DS_(Sh)) with ashort-chain component in a desired cellulose derivative. If theshort-chain reactant is excessively present, the binding amount of along-chain component decreases and the degree of substitution (DS_(Lo))with a long-chain component tends to decrease.

As the organic solvent, a solvent providing a liquid holding rate bycellulose: 90 vol % or more, is preferably used.

The “liquid holding rate” can be measured as follows.

Filter paper (5B, 40 mmϕ, water content: about 2%) made of cotton fiberis soaked in each solvent at room temperature for one hour. The weightsof the filter paper before and after soaking are measured and assignedto the following expression. In this manner, a liquid holding rate (vol%) is obtained. The weight of a sample after soaking is measured at thetime when dripping of a solvent from the sample is stopped.Liquid holding rate (vol %)=(weight after soaking−weight beforesoaking)/weight before soaking/specific gravity of solvent×100

Examples of a solvent providing a liquid holding rate of 90 vol % ormore, include water (liquid holding rate: 145 vol %), acetic acid(liquid holding rate: 109 vol %), dioxane (liquid holding rate: 93 vol%), pyridine (liquid holding rate: 109 vol %), N-methyl pyrrolidone(liquid holding rate: 104 vol %), N,N-dimethylacetamide (liquid holdingrate: 112 vol %), N,N-dimethylformamide (liquid holding rate: 129 vol %)and dimethylsulfoxide (liquid holding rate: 180 vol %).

An acid trapping component is not particularly limited as long as it isa base neutralizing an acid (e.g., hydrochloric acid, acetic acid,propionic acid) produced as a by-product. Examples thereof includealkaline metal hydroxides such as sodium hydroxide and potassiumhydroxide; alkaline earth metal hydroxides such as calcium hydroxide andbarium hydroxide; metal alkoxides such as sodium methoxide, sodiumethoxide; and nitrogen-containing nucleophilic compounds such asdiazabicycloundecene, diazabicyclononene, triethylamine and pyridine. Ofthem, triethylamine and pyridine are preferable, and pyridine isparticularly preferable since it can be used also as a solvent. When anacid trapping component is added independently of a solvent, it ispreferable that the acid trapping component is present in a reactionsystem from the initiation time of a reaction. As long as an acidtrapping component is present in a reaction system from the initiationtime of a reaction, an acid trapping component may be added before orafter addition of an acylating agent.

The addition amount of an acid trapping component relative to the totalamount of a starting long-chain reactant (long-chain acylating agent)and a starting short-chain reactant (short-chain acylating agent) ispreferably 0.1 to 10 equivalents and more preferably 0.5 to 5equivalents. However, when a nitrogen-containing nucleophilic compoundis used as a solvent, the addition amount of an acid trapping componentis not limited the above range. If the addition amount of an acidtrapping component is small, an acylation reaction efficiency decreases.In contrast, if the addition amount of an acid trapping component islarge, the cellulose may be decomposed and sometimes reduced inmolecular weight.

The reaction temperature in the acylation step is preferably 50 to 100°C. and more preferably 75 to 95° C. The reaction time can be set at 2hours to 5 hours and preferably 3 hours to 4 hours. If the reactiontemperature is sufficiently high, the reaction speed can be increased,with the result that an acylation reaction can be completed in arelative short time and the reaction efficiency can be increased. If thereaction temperature falls within the above range, a decrease inmolecular weight by heating can be suppressed.

The amount of an organic solvent can be set to be 10 to 50 times andpreferably 10 to 40 times (mass ratio) as large as the amount (dry mass)of the raw material pulp.

(Aging Step)

After the above acylation step, an aqueous alkaline solution is added,and the reaction solution is preferably held (aged) as it is whilewarming. The temperature during the aging is preferably 25 to 75° C. andpreferably 40 to 70° C. The time for aging can be set to fall within therange of 1 to 5 hours and preferably 1 to 3 hours.

The addition amount of an aqueous alkaline solution can be set so as tocorrespond to 3 to 30% by mass relative to the solvent to be used, andpreferably 5 to 20% by mass.

As the aqueous alkaline solution, aqueous solutions of, e.g., potassiumhydroxide, sodium carbonate and sodium hydrogen carbonate are mentioned,and an aqueous solution of sodium hydroxide is preferable. Theconcentration of an aqueous alkaline solution is preferably 1 to 30% bymass and more preferably 5 to 20% by mass.

Owing to such an aging step, the long-chain component and theshort-chain component once bound are partially hydrolyzed to come backto (homogeneous) hydroxy groups, with the result that mechanicalcharacteristics such as strength and impact resistance can be enhanced.In addition, in the following precipitation step, a product havingsatisfactory properties (fine granules) can be obtained.

(Recovery Step)

A cellulose derivative (product), which is formed by introducing along-chain component and a short-chain component, can be recovered froma reaction solution in accordance with a recovery method generally used.The recovery method is not limited; however, if a product is notdissolved in a reaction solution, a solid-liquid separation method forseparating a reaction solution and a product is preferable in view ofproduction energy. If it is difficult to separate a solid and a liquidbecause a product is dissolved in or compatible with a reactionsolution, the reaction solution is distilled off and a product can berecovered as the residue. Alternatively, a poor solvent for a product isadded to the reaction solution to precipitate the product, which may berecovered by solid-liquid separation.

When a reaction solution is distillated, it is preferable to use ashort-chain reactant, a reaction solvent and a catalyst having lowboiling points. The catalyst can be removed from a product with, e.g., awashing solvent without distillation. When components except a product,such as a solvent, are distilled away from a reaction solution,distillation is stopped when a product is precipitated, and then, theremaining reaction solution and the precipitated product can besubjected to solid-liquid separation to recovery the product.

As the solid-liquid separation method, e.g., filtration (naturalfiltration, filtration under reduced pressure, pressure filtration,centrifugal filtration and these while applying heat), spontaneoussedimentation and flotation, separation (by funnel), centrifugalseparation and squeeze, are mentioned. These can be used appropriatelyin combination.

A product (a cellulose derivative) dissolved in a filtrate after thesolid-liquid separation can be precipitated by adding a poor solvent forthe product and further subjected to solid-liquid separation to recoverit.

The solid content (a cellulose derivative) recovered from a reactionsolution is, if necessary washed and dried by a method generallyemployed.

The cellulose derivative produced by this method can possess areinforcing crystal structure due to a cellulose main-chain crystal in athermoplastic matrix. This is derived from an unreacted part when acellulose material is acylated. Such a cellulose main-chain crystal canbe evaluated, for example, by X-ray diffractometry. At the time ofevaluation, for example, a cellulose derivative can be pressed toincrease the density, thereby facilitating detection of a signal.

(Other Process for Producing Cellulose Derivative)

A cellulose resin can be obtained by acylating a cellulose in asolid-liquid heterogeneous system using a mixed acid anhydridecontaining a long-chain component and a short-chain component, as anacylating agent. Cellulose is preferably activated. The activationtreatment can be performed by a method generally used.

Acylation can be carried out in a solvent which provides a liquidholding rate of 90% or more (for example, dioxane, in an amount of,e.g., 80 to 120 times as large as the dry weight of pulp), in thepresence of an acid catalyst (for example, sulfuric acid) while stirringat 45 to 65° C. for 2 to 5 hours. Thereafter, it is preferable thatwater is added to age the reaction solution for a few hours (forexample, 1 to 3 hours) while heating (for example, 55 to 75° C.).

After completion of the reaction, a poor solvent such as awater/methanol solvent mixture, is added to allow a product dissolved inthe liquid phase to sufficiently precipitate, and then, solid-liquidseparation can be performed to recover a product. Thereafter, washingand drying can be made.

Acylation can be performed in a homogeneous solution system in which acellulose and an acylating agent are homogenously dissolved in asolvent. A cellulose is preferably activated. The activation treatmentcan be performed by a method generally used.

As a solvent for acylation, a solvent such as N,N-dimethylacetamide,which can dissolve a cellulose, is used.

As the acylating agent, a mixed acid anhydride having a long-chaincomponent and a short-chain component, which is produced in the samesolvent as the solvent to be used in acylation, can be used.

After completion of the reaction, a poor solvent such as methanol isadded to precipitate a product, which may be recovered by solid-liquidseparation. Thereafter, washing and drying can be made.

(Molding Resin Composition and Additives)

The cellulose derivative according to an exemplary embodiment canprovide a resin composition suitable as a molding material by addingadditives in accordance with desired properties. The cellulosederivative can be compatible with an additive which is compatible with ageneral cellulose derivative.

To the cellulose derivative according to an exemplary embodiment,various types of additives usually used in thermoplastic resins can beapplied. For example, if a plasticizer is added, thermoplasticity andbreaking elongation while breaking can be more improved. Examples ofsuch a plasticizer include phthalic esters such as dibutyl phthalate,diaryl phthalate, diethyl phthalate, dimethyl phthalate,di-2-methoxyethyl phthalate, ethyl phthalyl ethyl glycolate and methylphthalyl ethyl glycolate; tartaric acid esters such as dibutyl tartrate;adipic acid esters such as dioctyl adipate and diisononyl adipate;polyhydric alcohol esters such as triacetin, diacetyl glycerin,tripropionitrile glycerin and glyceryl monostearate; phosphoric acidesters such as triethyl phosphate, triphenyl phosphate and tricresylphosphate; dibasic fatty acid esters such as dibutyl adipate, dioctyladipate, dibutyl azelate, dioctyl azelate and dioctyl sebacate; citricacid esters such as triethyl citrate, acetyltriethyl citrate andtributyl acetylcitrate; epoxylated vegetable oils such as epoxylatedsoybean oil and epoxylated linseed oil; castor oil and a derivativethereof; benzoic acid esters such as ethyl O-benzoyl benzoate; aliphaticdicarboxylic acid esters such as sebacate and azelate; unsaturateddicarboxylic acid esters such as maleate; and N-ethyl toluenesulfonamide, triacetin, O-cresyl p-toluenesulfonate and tripropionin.Particularly of them, if a plasticizer such as dioctyl adipate, benzyladipate-2 butoxyethoxyethyl, tricresyl phosphate, diphenylcresylphosphate or diphenyl octyl phosphate is added, not onlythermoplasticity and breaking elongation but also shock resistance canbe effectively improved.

Examples of other plasticizers include cyclohexane dicarboxylic acidesters such as dihexyl cyclohexanedicarboxylate, dioctylcyclohexanedicarboxylate and di-2-methyloctyl cyclohexanedicarboxylate;trimellitic acid esters such as dihexyl trimellitate, diethylhexyltrimellitate and dioctyl trimellitate; and pyromellitic acid esters suchas dihexyl pyromellitate, diethylhexyl pyromellitate and dioctylpyromellitate.

To the cellulose derivative according to an exemplary embodiment, ifnecessary, an inorganic or organic granular or fibrous filler can beadded. By adding a filler, strength and rigidity can be more improved.Examples of the filler include, mineral particles (talc, mica, bakedsiliceous earth, kaolin, sericite, bentonite, smectite, clay, silica,quartz powder, glass beads, glass powder, glass flake, milled fiber,Wollastonite, etc.), boron-containing compounds (boron nitride, boroncarbonate, titanium boride etc.), metal carbonates (magnesium carbonate,heavy calcium carbonate, light calcium carbonate, etc.), metal silicates(calcium silicate, aluminum silicate, magnesium silicate, magnesiumaluminosilicate, etc.), metal oxides (magnesium oxide etc.), metalhydroxides (aluminum hydroxide, calcium hydroxide, magnesium hydroxide,etc.), metal sulfates (calcium sulfate, barium sulfate, etc.), metalcarbides (silicon carbide, aluminum carbide, titanium carbide, etc.),metal nitrides (aluminum nitride, silicon nitride, titanium nitride,etc.), white carbon and metal foils. Examples of the fibrous fillerinclude organic fibers (natural fiber, papers etc.), inorganic fibers(glass fiber, asbestos fiber, carbon fiber, silica fiber, silica aluminafiber, Wollastonite, zirconia fiber, potassium titanate fiber etc.) andmetal fibers. These fillers can be used singly or in combination of twoor more types.

To the cellulose derivative according to an exemplary embodiment, ifnecessary, a flame retardant can be added. By adding a flame retardant,flame resistance can be imparted. Examples of the flame retardantinclude metal hydrates such as magnesium hydroxide, aluminum hydroxideand hydrotalcite, basic magnesium carbonate, calcium carbonate, silica,alumina, talc, clay, zeolite, bromine-based flame retardant, antimonytrioxide, phosphoric acid based flame retardant (aromatic phosphate,aromatic condensed phosphate, etc.), compounds containing phosphorus andnitrogen (phosphazene compound), etc. These flame retardants can be usedsingly or in combination with two or more types.

To the cellulose derivative according to an exemplary embodiment, ifnecessary, a shock resistance improver can be added. By adding a shockresistance improver, shock resistance can be improved. Examples of theshock resistance improver include a rubber component and a siliconecompound. Examples of the rubber component include a natural rubber,epoxylated natural rubber and synthesized rubber. Furthermore, examplesof the silicone compound include organic polysiloxane formed bypolymerization of alkyl siloxane, alkyl phenyl siloxane, etc. andmodified silicone compounds obtained by modifying a side chain or an endof an organic polysiloxane as mentioned above with polyether,methylstyryl, alkyl, higher fatty acid ester, alkoxy, fluorine, an aminogroup, an epoxy group, a carboxyl group, a carbinol group, a methacrylgroup, a mercapto group, a phenol group etc. These shock resistanceimprovers can be used singly or in combination of two or more types.

As the silicone compound, a modified silicone compound (modifiedpolysiloxane compound) is preferred. As the modified silicone compound,a modified polydimethyl siloxane is preferred, which has a structurehaving a main chain constituted of dimethyl siloxane repeat units and aside chain or a terminal methyl group partly substituted with an organicsubstituent containing at least one group selected from an amino group,an epoxy group, a carbinol group, a phenol group, a mercapto group, acarboxyl group, a methacryl group, a long-chain alkyl group, an aralkylgroup, a phenyl group, a phenoxy group, an alkyl phenoxy group, along-chain fatty acid ester group, a long-chain fatty acid amide groupand a polyether group. The modified silicone compound, because of thepresence of such an organic substituent, is improved in affinity for theaforementioned cellulose derivative and dispersibility in the cellulosederivative is improved. Consequently, a resin composition excellent inshock resistance can be obtained.

As such a modified silicone compound, a modified silicone compoundproduced in accordance with a conventional method can be used.

Examples of the organic substituent contained in the modified siliconecompound include the organic substituents represented by the followingformulas (2) to (20) are mentioned:

where a and b each represent an integer of 1 to 50.

In the aforementioned formulas, R¹ to R¹⁰, R¹² to R¹⁵, R¹⁹ and R²¹ eachrepresent a divalent organic group. Examples of the divalent organicgroup include alkylene groups such as a methylene group, an ethylenegroup, a propylene group and a butylene group; alkyl arylene groups suchas a phenylene group and a tolylene group; oxyalkylene groups andpolyoxyalkylene groups such as —(CH₂—CH₂—O)c- (c represents an integerfrom 1 to 50), —[CH₂—CH (CH₃)—O]_(d)— (d represents an integer from 1 to50), and —(CH₂)e-NHCO— (e represents an integer from 1 to 8). Of these,an alkylene group is preferable and particularly, an ethylene group anda propylene group are preferable.

In the aforementioned formulas, R¹¹, R¹⁶ to R¹⁸, R²⁰ and R²² eachrepresent an alkyl group having at most 20 carbon atoms. Examples of thealkyl group include a methyl group, an ethyl group, a propyl group, abutyl group, a pentyl group, a hexyl group, a heptyl group, an octylgroup, a nonyl group, a decyl group, an undecyl group, a dodecyl group,a tridecyl group, a tetradecyl group and a pentadecyl group.Furthermore, the structures of the above alkyl groups may have one ormore unsaturated bonds.

The total average content of organic substituents in a modified siliconecompound desirably falls within the range where the modified siliconecompound having an appropriate particle diameter (for example, 0.1 μm ormore and 100 μm or less) can be dispersed in a matrix, i.e., a cellulosederivative, during a process for producing a cellulose derivativecomposition. If a modified silicone compound having an appropriateparticle diameter is dispersed in a cellulose derivative, stressconcentration on the periphery of a silicone region having a low elasticmodulus effectively occurs. As a result, a resin molded body havingexcellent shock resistance can be obtained. The total average content ofsuch organic substituents is preferably 0.01% by mass or more and morepreferably 0.1% by mass or more, and also preferably 70% by mass or lessand more preferably 50% by mass or less. If an organic substituent iscontained appropriately, the modified silicone compound can be improvedin affinity for a cellulose resin, the modified silicone compound havingan appropriate particle diameter can be dispersed in a cellulosederivative, and further bleed out due to separation of the modifiedsilicone compound in a molding can be suppressed. If the total averagecontent of the organic substituents is excessively low, it becomesdifficult to disperse a modified silicone compound having an appropriateparticle diameter in a cardanol-added cellulose resin.

If an organic substituent of the modified polydimethyl siloxane compoundis an amino group, an epoxy group, a carbinol group, a phenol group, amercapto group, a carboxyl group or a methacryl group, the averagecontent of the organic substituent in the modified polydimethyl siloxanecompound can be obtained by the following Expression (I).Organic substituent average content (%)=(organic substituentformula−weight/organic substituent equivalent)×100  (I)

In the Expression (I), the organic substituent equivalent is an averagemass of a modified silicone compound per organic substituent (1 mole).

When the organic substituent of the modified polydimethyl siloxanecompound is a phenoxy group, an alkylphenoxy group, a long-chain alkylgroup, an aralkyl group, a long-chain fatty acid ester group or along-chain fatty acid amide group, the average content of the organicsubstituent of the modified polydimethyl siloxane compound can beobtained from the following Expression (II).Organic substituent average content(%)=x×w/[(1−x)×74+x×(59+w)]×100  (II)

In the Expression (II), x is an average molar fraction of the organicsubstituent-containing a siloxane repeat unit relative to all siloxanerepeat units of the modified polydimethyl siloxane compound; and w isthe formula weight of the organic substituent.

In the case where the organic substituent of the modified polydimethylsiloxane compound is a phenyl group, the average content of the phenylgroup in the modified polydimethyl siloxane compound can be obtained bythe following Expression (III).Phenyl group average content (%)=154×x/[74×(1−x)+198×x]×100  (III)

In the Expression (III), x is an average molar fraction of the phenylgroup-containing siloxane repeat unit relative to all siloxane repeatunits in the modified polydimethyl siloxane compound (A).

In the case where the organic substituent of the modified polydimethylsiloxane compound is a polyether group, the average content of thepolyether group in the modified polydimethyl siloxane compound can beobtained by the following Expression (IV).Polyether group average content (%)=HLB value/20×100  (IV)

In the Expression (IV), the HLB value represents the degree of affinityof a surfactant for water and oil, and is defined by the followingExpression (V) based on the Griffin Act.HLB value=20×(sum of formula weights of hydrophilic moieties/molecularweight)   (V)

To the cellulose derivative of the exemplary embodiment, two or moremodified silicone compounds having different affinities to thederivative may be added. In this case, dispersibility of a relativelow-affinity modified silicone compound (A1) is improved by a relativehigh-affinity modified silicone compound (A2) to obtain a celluloseresin composition having even more excellent shock resistance. The totalaverage content of an organic substituent of the relatively low-affinitymodified silicone compound (A1) is preferably 0.01% by mass or more andmore preferably 0.1% by mass or more and also preferably 15% by mass orless and more preferably 10% by mass or less. The total average contentof an organic substituent of the relatively high-affinity modifiedsilicone compound (A2) is preferably 15% by mass or more and morepreferably 20% by mass or more and also preferably 90% by mass or less.

The blending ratio (mass ratio) of the modified silicone compound (A1)to the modified silicone compound (A2) can be set to fall within therange of 10/90 to 90/10.

In a modified silicone compound, dimethyl siloxane repeat units andorganic substituent-containing siloxane repeat units each of which maybe homologously and continuously connected, alternately connected orconnected at random. A modified silicone compound may have a branchedstructure.

The number average molecular weight of a modified silicone compound ispreferably 900 or more and more preferably 1000 or more, and alsopreferably 1000000 or less, more preferably 300000 or less and furtherpreferably 100000 or less. If the molecular weight of a modifiedsilicone compound is sufficiently large, loss by vaporization can besuppressed in kneading with a melted cellulose derivative during aprocess for producing a cellulose derivative composition. Furthermore,if the molecular weight of a modified silicone compound is appropriate(not excessively large), a uniform molding having good dispersibilitycan be obtained.

As the number average molecular weight, a value (calibrated by apolystyrene standard sample) obtained by measuring a 0.1% chloroformsolution of a sample by GPC can be employed.

The addition amount of such a modified silicone compound is preferably,in view of obtaining sufficient addition effect, 1% by mass or morerelative to the total cellulose derivative composition and morepreferably 2% by mass or more. In view of sufficiently ensuringproperties of a cellulose resin such as strength and suppressing bleedout, the addition amount of a modified silicone compound is preferably20% by mass or less and more preferably 10% by mass or less.

By adding such a modified silicone compound to a cellulose derivative,the modified silicone compound having an appropriate particle diameter(for example, 0.1 to 100 μm) can be dispersed in the resin and the shockresistance of a resin composition can be improved.

To the cellulose derivative of the exemplary embodiment, if necessary,additives such as a colorant, an antioxidant and a heat stabilizer maybe added as long as they are applied to conventional resin compositions.

To the cellulose derivative of the exemplary embodiment, if necessary, ageneral thermoplastic resin may be added.

As the thermoplastic resin, a polyester can be added and astraight-chain aliphatic polyester can be preferably used. As thestraight-chain aliphatic polyester (Y), the following straight-chainaliphatic polyesters (Y1) and (Y2) are preferable, for example,polybutylene succinate, polybutylene succinate adipate andpolycaprolactone can be mentioned.

(Y1) Straight-chain aliphatic polyester containing at least one ofrepeating units represented by the following formula (21) and formula(22)—(CO—R²³—COO—R²⁴—O—)—  (21)—(CO—R²⁵—O—)—  (22)

In the formula (21), R²³ represents a divalent aliphatic group havingcarbon atoms of 1 to 12, preferably 2 to 8 and more preferably 2 to 4;and R²⁴ represents a divalent aliphatic group having carbon atoms of 2to 12, preferably 2 to 8 and more preferably 2 to 4.

In the formula (22), R²⁵ represents a divalent aliphatic group havingcarbon atoms of 2 to 10, preferably 2 to 8 and more preferably 2 to 4.

(Y2) Straight-chain aliphatic polyester composed of a product obtainedby ring-opening polymerization of a cyclic ester.

The straight-chain aliphatic polyester (Y1) can be obtained by acondensation reaction between at least one selected from the groupconsisting of, for example, an aliphatic dicarboxylic acid, an acidanhydride thereof and a diester thereof, and an aliphatic diol.

The aliphatic dicarboxylic acid has carbon atoms of, for example, 3 to12, preferably 3 to 9, more preferably 3 to 5. The aliphatic carboxylicacid is, for example, an alkane dicarboxylic acid. Specific examplesthereof include malonic acid, succinic acid, adipic acid, sebacic acid,azelaic acid and dodecane dicarboxylic acid. The aliphatic dicarboxylicacids, for example, may be used alone or in combination of two or more.

The aliphatic diol has carbon atoms of, for example, 2 to 12, preferably2 to 8 and more preferably 2 to 6. The aliphatic diol is, for example,an alkylene glycol. Specific examples thereof include ethylene glycol,1,3-propylene glycol, 1,4-butane diol, 1,6-hexane diol, 1,9-nonane diol,1,10-decane diol and 1,12-dodecane diol. Of them, a straight-chainaliphatic diol having 2 to 6 carbon atoms is preferable, andparticularly, ethylene glycol, 1,3-propylene glycol, 1,4-butane diol and1,6-hexane diol are preferable. The aliphatic diols, for example, may beused alone or in combination of two or more.

The straight-chain aliphatic polyester (Y2) is a straight-chainaliphatic polyester obtained by ring-opening polymerization of a cyclicester. The cyclic ester is, for example, lactone having carbon atoms of2 to 12. Specific examples thereof include, α-acetolactone,β-propiolactone, γ-butyrolactone and δ-valerolactone. The cyclic esters,for example, may be used alone or in combination with two or more.

The number average molecular weight of the straight-chain aliphaticpolyester (Y) is not particularly limited. The lower limit thereof ispreferably, for example, 10000 or more, and more preferably 20000 ormore. The upper limit thereof is preferably, for example, 200000 or lessand more preferably 100000 or less. The aliphatic polyester having amolecular weight within the above range can provide, for example, a moreuniform molded body having more excellent dispersibility.

As the number average molecular weight, for example, a value (calibratedby a polystyrene standard sample) obtained by measuring a 0.1%chloroform solution of a sample by GPC can be employed.

By adding a thermoplastic resin having excellent flexibility such as athermoplastic polyurethane elastomer (TPU) to the cellulose derivativeaccording to an exemplary embodiment, shock resistance can be improved.The addition amount of such a thermoplastic resin (particularly, TPU)is, in view of obtaining sufficient addition effect, preferably 1% bymass or more and more preferably 5% by mass or more relative to thetotal composition containing the cellulose resin of the exemplaryembodiment.

The thermoplastic polyurethane elastomer (TPU) suitable for improvingshock resistance that can be used includes a polyurethane elastomerprepared by using a polyol, a diisocyanate and a chain extender.

Examples of the polyol include polyester polyol, polyester ether polyol,polycarbonate polyol and polyether polyol.

Examples of the polyester polyol include a polyester polyol obtained bya dehydration condensation reaction between a polyvalent carboxylic acidsuch as an aliphatic dicarboxylic acid (succinic acid, adipic acid,sebacic acid, azelaic acid, etc.), an aromatic dicarboxylic acid(phthalic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, etc.), an alicyclic dicarboxylic acid(hexahydrophthalic acid, hexahydroterephthalic acid,hexahydroisophthalic acid, etc.), or an acid ester or an acid anhydrideof each of these, and a polyol such as ethylene glycol, 1,3-propyleneglycol, 1,2-propylene glycol, 1,3-butane diol, 1,4-butane diol,1,5-pentane diol, 1,6-hexane diol, 3-methyl-1,5-pentane diol, neopentylglycol, 1,3-octane diol, 1,9-nonane diol, or a mixture of these; and apolylactone diol obtained by ring-opening polymerization of a lactonemonomer such as ε-caprolactone.

Examples of the polyester ether polyol include a compound obtained by adehydration condensation reaction between a polyvalent carboxylic acidsuch as an aliphatic dicarboxylic acid (succinic acid, adipic acid,sebacic acid, azelaic acid, etc.), an aromatic dicarboxylic acid(phthalic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, etc.), an alicyclic dicarboxylic acid(hexahydrophthalic acid, hexahydroterephthalic acid,hexahydroisophthalic acid, etc.), or an acid ester or an acid anhydrideof each of these, and a glycol such as diethylene glycol or an alkyleneoxide adduct (propylene oxide adduct etc.) or a mixture of these.

Examples of the polycarbonate polyol include a polycarbonate polyolobtained by reacting one or two or more polyols such as ethylene glycol,1,3-propylene glycol, 1,2-propylene glycol, 1,3-butane diol, 1,4-butanediol, 1,5-pentane diol, 1,6-hexane diol, 3-methyl-1,5-pentane diol,neopentyl glycol, 1,8-octane diol, 1,9-nonane diol and diethylene glycolwith diethylene carbonate, dimethyl carbonate, diethyl carbonate, etc.;and further may include a copolymer of a polycaprolactone polyol (PCL)and a polyhexamethylene carbonate (PHL).

Examples of the polyether polyol include a polyethylene glycol,polypropylene glycol and polytetramethylene ether glycol, each of whichis obtained by polymerizing respective cyclic ethers: ethylene oxide,propylene oxide and tetrahydrofuran; and copolyethers of these.

Examples of the diisocyanate to be used in formation of TPU includetolylene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI),1,5-naphthylene diisocyanate (NDI), tolidine diisocyanate,1,6-hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI),xylylene diisocyanate (XDI), hydrogenated XDI, triisocyanate,tetramethyl xylene diisocyanate (TMXDI), 1,6,11-undecane triisocyanate,1,8-diisocyanatemethyl octane, lysine ester triisocyanate,1,3,6-hexamethylene triisocyanate, bicycloheptane triisocyanate anddicyclohexyl methane diisocyanate (hydrogenated MDI; HMDI). Of these,4,4′-diphenylmethane diisocyanate (MDI) and 1,6-hexamethylenediisocyanate (HDI) are preferably used.

Examples of the chain extender to be used in formation of TPU, alow-molecular weight polyol can be used. Examples of the low-molecularweight polyol include aliphatic polyols such as ethylene glycol,1,3-propylene glycol, 1,2-propylene glycol, 1,3-butane diol, 1,4-butanediol, 1,5-pentane diol, 1,6-hexane diol, 3-methyl-1,5-pentane diol,neopentyl glycol, 1,8-octane diol, 1,9-nonane diol, diethylene glycoland 1,4-cyclohexane dimethanol and glycerin; and aromatic glycols suchas 1,4-dimethylolbenzene, bisphenol A and ethylene oxide or a propyleneoxide adduct of bisphenol A.

When a silicone compound is copolymerized with a thermoplasticpolyurethane elastomer (TPU) obtained from these materials, furtherexcellent shock resistance can be obtained.

These thermoplastic polyurethane elastomers (TPU) may be used singly orin combination.

A process for producing a resin composition containing the cellulosederivative according to an exemplary embodiment, additives and athermoplastic resin, is not particularly limited. For example, the resincomposition can be produced by melting and mixing additives and thecellulose resin manually by handmixing or by use of a known mixer suchas a tumbler mixer, or a ribbon blender, a single-axial or a multiaxialmixing extruder, and a compounding apparatus such as a kneader andkneading roll and, if necessary, granulating the mixture into anappropriate shape. In another preferable process, additives dispersed insolvent such as an organic solvent and a resin are mixed andfurthermore, if necessary, a coagulation solvent is added to obtain amixed composition of the additives and the resin and thereafter, thesolvent is evaporated.

The cellulose resin according to the exemplary embodiments mentionedabove can be used as a base resin for a molding material (resincomposition). The molding material using the cellulose resin as a baseresin is suitable for forming a molded body such as housing, e.g.packaging for an electronic device.

The base resin herein refers to a main component of the molding materialand means that other components may be contained as long as thecomponents do not prevent the function of the main component. Thecontent rate of the main component is not particularly limited; however,the content rate of the main component in a composition is 50% by massor more, preferably 70% by mass or more, more preferably 80% by mass ormore and particularly preferably 90% by mass or more.

EXAMPLES

Hereinafter, the present invention will be described in more detail withreference to specific examples.

[Measurement of Polymerization of Pulp]

The limiting viscosities [η] of the pulp used for producing thecellulose resins were measured in accordance with the JIS P8215, and thedegree of polymerization (DP) of the pulp was calculated according tothe equation (VI). The results are given in Table 1. The value of DPshown in Table 1 is the degree of polymerization of the pulp used in thepreparation of the cellulose resin of each example and each comparativeexample.[η]=1.67×DP ^(0.71)  (VI)

Example 1

After the activation treatment of cellulose (pulp), the cellulose (pulp)was acylated in a solid-liquid heterogeneous system to obtain acellulose resin. Specifically, the cellulose resin (cellulose propionatestearate) was prepared according to the following.

Six grams (in terms of dry weight, 37 mmol/glucose unit) of Cellulose 1(dissolving pulp powder, water content 6.4%, DP560) was put in a reactorand dispersed in 90 ml of pyridine in a nitrogen atmosphere, and stirredovernight at room temperature for activation.

Thereafter, the cellulose dispersion was cooled to 10° C. or less, and7.85 g (26 mmol) of stearoyl chloride and 10.28 g (111 mmol) ofpropionyl chloride were mixed in advance and charged into the reactorwhile maintaining 10° C. or less.

After stirring with heating at 100° C. for 4 hours, the mixture wascooled to 50° C., 125 ml of methanol was added dropwise, and the mixturewas stirred for about 30 minutes.

An additional 40 ml of water was added to precipitate the product, whichwas collected by suction filtration. The resulting solid was washed with100 ml of methanol (4 times) until the color of the filtratedisappeared.

The washed solid content was dried in vacuo at 105° C. for 5 hours toobtain 13.8 g (yield 97%) of a powdery cellulose resin (cellulosepropionate stearate).

The obtained sample (cellulose propionate stearate) was measured by¹H-NMR (AV-400, manufactured by Bruker Corporation, 400 MH_(z), solvent:CDCl₃ (partial dissolution)), and as a result, DS_(Lo) was 0.41, andDS_(Sh) was 2.00.

This sample was evaluated according to the following. The results areshown in Table 1.

[Preparation of Injection Molded Body]

A molded body having the following shape was formed from the samplesobtained above by using an injection molding machine (HAAKE MiniJet II,manufactured by Thermo Electron Corporation).

Size of the molded body: thickness: 2.4 mm, width: 12.4 mm, length: 80mm

The molding was performed in the conditions: cylinder temperature of themolding machine: 220° C., temperature of a mold: 60° C., injectionpressure: 1200 bar (120 MPa) for 5 seconds and holding pressure: 600 bar(60 MPa) for 20 seconds.

[Measurement of Izod Impact Strength]

The molded bodies obtained above were subjected to measurement ofnotched Izod impact strength performed in the conditions described inJIS K7110.

The obtained data were evaluated in accordance with the followingcriteria.

Criteria for evaluation of Izod impact strength:

◯: 5.0 kJ/m² or more

x: less than 5.0 kJ/m²

[Measurement of Flowability (Melt Flow Rate (MFR))]

MFRs were measured using a high-pressure type flow tester (manufacturedby Shimadzu Corporation, product name: CFT-500D) at temperatures of 200°C., under a load of 5 kg, a die of 2 mmφ×10 mm (diameter of hole 2 mm,length of hole 10 mm), and preheating of 2 minutes (period from the timewhen a sample is filled in a cylinder and a piston is inserted to thetime when the load is applied), based on JIS7210:1990.

The obtained data were evaluated in accordance with the followingcriteria.

MFR evaluation criteria

◯: 10 g/10 min or more

x: less than 10 g/10 min

Example 2

A cellulose resin (cellulose propionate stearate) was obtained inaccordance with the same quantities and method as in Example 1 exceptthat the raw material was changed to cellulose 2 (dissolving pulppowder, water content 6.1%, DP460) (amount of product 13 3 g, yield96%).

The obtained sample (cellulose propionate stearate) was measured by¹H-NMR in the same manner as in Example 1, and as a result, DS_(Lo) was0.39 and DS_(Sh) was 2.09.

The sample was evaluated for impact strength and flowability in the samemanner as in Example 1. The results are shown in Table 1.

Example 3

A cellulose resin (cellulose propionate stearate) was prepared accordingto the following.

Six grams (in terms of dry weight, 37 mmol/glucose unit) of Cellulose 1(dissolving pulp powder, water content 6.4%, DP560) was put in a reactorand dispersed in a mixture of 79 ml of N-methylpyrrolidone (NMP) and 11ml of pyridine in a nitrogen-atmosphere, and stirred overnight at roomtemperature for activation.

Thereafter, the cellulose dispersion was cooled to 10° C. or less, and5.60 g (18 mmol) of stearoyl chloride and 10.28 g (111 mmol) ofpropionyl chloride were mixed in advance and charged into the reactorwhile maintaining 10° C. or less.

After stirring with heating at 90° C. for 4 hours, the mixture wascooled to 50° C., 90 ml of methanol was added dropwise, and the mixturewas stirred for about 30 minutes.

An additional 20 ml of water was added to precipitate the product, whichwas collected by suction filtration. The resulting solid was washed with100 ml of methanol (4 times) until the color of the filtratedisappeared.

The washed solid content was dried in vacuo at 105° C. for 5 hours toobtain 12. 6 g (yield 92%) of a powdery cellulose resin (cellulosepropionate stearate).

The obtained sample (cellulose propionate stearate) was measured by¹H-NMR (AV-400, manufactured by Bruker Corporation, 400 MHz, solvent:CDCl₃ (partial dissolution), and as a result, DS_(Lo) was 0.32, andDS_(Sh) was 2.21.

This sample was evaluated for impact strength and flowability in thesame manner as in Example 1. The results are shown in Table 1.

Example 4

A cellulose resin (cellulose propionate stearate) was obtained inaccordance with the same quantities and method as in Example 3 exceptthat the raw material was changed to cellulose 2 (dissolving pulppowder, water content 6.1%, DP460) (amount of product 12 4 g, yield89%).

The obtained sample (cellulose propionate stearate) was measured by¹H-NMR in the same manner as in Example 1, and as a result, DS_(Lo) was0.33 and DS_(Sh) was 2.24.

The sample was evaluated for impact strength and flowability in the samemanner as in Example 1. The results are shown in Table 1.

Comparative Example 1

A cellulose resin (cellulose propionate stearate) was obtained inaccordance with the same quantities and method as in Example 1 exceptthat the raw material was changed to cellulose 3 (dissolving pulppowder, water content 3.5%, DP1090) (amount of product 14 5 g, yield99%).

The obtained sample (cellulose propionate stearate) was measured by¹H-NMR in the same manner as in Example 1, and as a result, DS_(Lo) was0.44 and DS_(Sh) was 2.05.

The sample was evaluated for impact strength and flowability in the samemanner as in Example 1. The results are shown in Table 1.

Comparative Example 2

A cellulose resin (cellulose propionate stearate) was obtained inaccordance with the same quantities and method as in Example 1 exceptthat the raw material was changed to cellulose 4 (dissolving pulppowder, water content 6.2%, DP850) (amount of product 14 3 g, yield99%).

The obtained sample (cellulose propionate stearate) was measured by¹H-NMR in the same manner as in Example 1, and as a result, DS_(Lo) was0.44 and DS_(Sh) was 1.98.

The sample was evaluated for impact strength and flowability in the samemanner as in Example 1. The results are shown in Table 1.

Comparative Example 3

A cellulose resin (cellulose propionate stearate) was obtained inaccordance with the same quantities and method as in Example 1 exceptthat the raw material was changed to cellulose 5 (dissolving pulppowder, water content 7.3%, DP250) (amount of product 14. 1 g, yield98%).

The obtained sample (cellulose propionate stearate) was measured by¹H-NMR in the same manner as in Example 1, and as a result, DS_(Lo) was0.39 and DS_(Sh) was 2.07.

The sample was evaluated for impact strength and flowability in the samemanner as in Example 1. The results are shown in Table 1.

Comparative Example 4

A cellulose resin (cellulose propionate stearate) was obtained inaccordance with the same quantities and method as in Example 3 exceptthat the raw material was changed to cellulose 4 (dissolving pulppowder, water content 6.2%, DP850) (amount of product 12 2 g, yield91%).

The obtained sample (cellulose propionate stearate) was measured by¹H-NMR in the same manner as in Example 1, and as a result, DS_(Lo) was0.30 and DS_(Sh) was 2.14.

The sample was evaluated for impact strength and flowability in the samemanner as in Example 1. The results are shown in Table 1.

Comparative Example 5

A cellulose resin (cellulose propionate stearate) was obtained inaccordance with the same quantities and method as in Example 3 exceptthat the raw material was changed to cellulose 5 (dissolving pulppowder, water content 7.3%, DP250) (amount of product 10. 5 g, yield76%).

The obtained sample (cellulose propionate stearate) was measured by¹H-NMR in the same manner as in Example 1, and as a result, DS_(Lo) was0.33 and DS_(Sh) was 2.19.

The sample was evaluated for impact strength and flowability in the samemanner as in Example 1. The results are shown in Table 1.

Table 1 summarizes the long-chain component (octadecanoyl group(corresponding to the acyl group portion contained in stearic acid)),the short-chain component (propionyl group) and degrees of substitution,and evaluation results of impact strength and flowability of eachcellulose resin (cellulose propionate stearate) produced.

TABLE 1 Degree of Long-chain Short-chain Impact FlowabilityPolymerization Reaction component component strength (MFR) Pulp (DP)Solvent (DS_(Lo)) (DS_(Sh)) DS_(Lo) + DS_(Sh) DS_(Sh)/DS_(Lo) [kJ/m²][g/10 min] Example 1 Cellulose 1 560 pyridine 0.41 2.00 2.41 4.9 13.3 53   ∘ ∘ Example 2 Cellulose 2 460 pyridine 0.39 2.09 2.48 5.4 8.2 74  ∘ ∘ Example 3 Cellulose 1 560 NMP/pyridine 0.32 2.21 2.53 6.9 14.9  61  ∘ ∘ Example 4 Cellulose 2 460 NMP/pyridine 0.33 2.24 2.57 6.8 9.8 145   ∘ ∘ Comparative Cellulose 3 1090 pyridine 0.44 2.05 2.49 4.7 3.6 0.5Example 1 x x Comparative Cellulose 4 850 pyridine 0.44 1.98 2.42 4.54.4 1.1 Example 2 x x Comparative Cellulose 5 250 pyridine 0.39 2.072.46 5.3 3.3 136    Example 3 x ∘ Comparative Cellulose 4 850NMP/pyridine 0.30 2.14 2.44 7.1 6.2 7.3 Example 4 ∘ x ComparativeCellulose 5 250 NMP/pyridine 0.33 2.19 2.52 6.6 3.4 330    Example 5 x ∘

As shown in Table 1, the cellulose resins of the examples according tothe exemplary embodiments of the present invention are excellent inmechanical characteristics (impact strength) and thermoplasticity(flowability).

On the other hand, it can be seen that the cellulose resins of thecomparative examples produced using pulp (raw material cellulose) havinga degree of polymerization not in the range of 300 to 700 are inferiorin mechanical characteristics as compared with the cellulose resins ofthe examples.

Specifically, it can be seen that the cellulose resins of ComparativeExamples 1 and 2 using pulp having a degree of polymerization of greaterthan 700 have high inhomogeneity and poor impact strength, and haveinsufficient thermoplasticity. In the cellulose resin of ComparativeExample 4 using pulp having a degree of polymerization of greater than700, the impact strength is better than that of the other ComparativeExamples, but the impact strength is inferior to that of the Examples,and the thermoplasticity is insufficient. On the contrary, the celluloseresins of Comparative Examples 3 and 5 using pulp having a degree ofpolymerization of less than 300 are excellent in thermoplasticity butinferior in impact strength.

Having thus described the present invention with reference to theexemplary embodiments and Examples, the present invention is not limitedto the above-described exemplary embodiments and Examples. Variousmodifications understandable to those skilled in the art may be made tothe constitution and details of the present invention within the scopethereof.

Some or the whole of the above exemplary embodiments can be describedalso as the following exemplary embodiments, but is not limited to thefollowing.

Further Exemplary Embodiment 1

A cellulose resin formed by substituting hydrogen atoms of hydroxygroups of a cellulose with a long-chain component being a linearsaturated aliphatic acyl group having 14 or more carbon atoms and ashort-chain component being an acyl group (propionyl group) having 3carbon atoms,

wherein a degree of substitution with the long-chain component (DS_(Lo))and a degree of substitution with the short-chain component (DS_(Sh))satisfy the following conditional expressions (1) and (2):DS _(Lo) +DS _(Sh)≥2.1  (1)4≤DS _(Sh) /DS _(Lo)≤12  (2),

Izod impact strength is 5.0 kJ/m² or more, and

an MFR (melt flow rate at 200□ and under a load of 5 kg) is 10 g/10 minor more.

Further exemplary embodiment 2

The cellulose resin according to Further exemplary embodiment 1, whereinDS_(Lo)+DS_(Sh) is in the range of 2.1 to 2.6, DS_(Lo) is in the rangeof 0.3 to 0.5, and DS_(Sh) is in the range of 1.9 to 2.3.

Further Exemplary Embodiment 3

The cellulose resin according to Further exemplary embodiment 2, whereinDS_(Lo)+DS_(Sh) is in the range of 2.25 to 2.6.

Further Exemplary Embodiment 4

The cellulose resin according to Further exemplary embodiment 2 or 3,wherein the DS_(Sh) is in the range 1.9 to 2.2.

Further Exemplary Embodiment 5

The cellulose resin according to any one of Further exemplaryembodiments 1 to 4, wherein the polymerization degree of the celluloseis in the range of 300 to 700.

Further Exemplary Embodiment 6

The cellulose resin according to any one of Further exemplaryembodiments 1 to 5, wherein the long-chain component is an acyl groupmoiety of at least one fatty acid selected from myristic acid, palmiticacid, stearic acid, arachidic acid, and behenic acid.

Further Exemplary Embodiment 7

A molding material comprising the cellulose resin according to any oneof Further exemplary embodiments 1 to 6.

Further Exemplary Embodiment 8

A molded body formed by using the molding material according to Furtherexemplary embodiment 7.

Further Exemplary Embodiment 9

A method for producing the cellulose resin according to any one ofFurther exemplary embodiments 1 to 4, comprising:

acylating hydroxy groups of a cellulose constituting a pulp by reacting

-   -   the pulp having a polymerization degree of 300 to 700 and        dispersed in an organic solvent with    -   propionyl chloride, and    -   a long-chain reactant being an acid chloride of a long-chain        fatty acid and comprising the long-chain component,    -   in the presence of the acid trapping component and under        warming; and

separating an acylated cellulose obtained in the acylating from theorganic solvent.

Further Exemplary Embodiment 10

The method for producing the cellulose resin according to Furtherexemplary embodiment 9, wherein the organic solvent is a solventproviding a liquid holding rate by the cellulose of 90% by volume ormore.

Further Exemplary Embodiment 11

The method for producing the cellulose resin according to Furtherexemplary embodiment 9 or 10, wherein the organic solvent is at leastone selected from water, acetic acid, dioxane, pyridine,N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, anddimethyl sulfoxide.

Further Exemplary Embodiment 12

The method for producing the cellulose resin according to any one ofFurther exemplary embodiments 9 to 11, wherein the acid trappingcomponent comprises a nitrogen-containing nucleophilic compound.

Further Exemplary Embodiment 13

The method for producing the cellulose resin according to any one ofFurther exemplary embodiments 9 to 11, wherein a nitrogen-containingnucleophilic compound is used as the acid trapping component and thesolvent.

Further Exemplary Embodiment 14

The method for producing the cellulose resin according to any one ofFurther exemplary embodiments 9 to 13, wherein the acid trappingcomponent comprises triethylamine or pyridine.

Further Exemplary Embodiment 15

The method for producing the cellulose resin according to any one ofFurther exemplary embodiments 9 to 13, wherein the acid trappingcomponent comprises pyridine.

Further Exemplary Embodiment 16

The method for producing the cellulose resin according to any one ofFurther exemplary embodiments 9 to 15, wherein the amount of the organicsolvent is 10 to 50 times as large as the dry mass of the pulp.

Further Exemplary Embodiment 17

The method for producing a cellulose resin according to any one ofFurther exemplary embodiments 9 to 16, wherein the acid chloride of thelong-chain fatty acid is at least one selected from the acid chloride ofmyristic acid, the acid chloride of palmitic acid, the acid chloride ofstearic acid, the acid chloride of arachidic acid, and the acid chlorideof behenic acid.

The invention claimed is:
 1. A cellulose resin formed by substitutinghydrogen atoms of hydroxy groups of a cellulose with a long-chaincomponent being a linear saturated aliphatic acyl group having 14 ormore carbon atoms and a short-chain component being an acyl group(propionyl group) having 3 carbon atoms, wherein a degree ofsubstitution with the long-chain component (DS_(Lo)) and a degree ofsubstitution with the short-chain component (DS_(Sh)) satisfy thefollowing conditional expressions (1) and (2):2.1≤DS _(Lo) +DS _(Sh)≤2.6  (1),4≤DS _(Sh) /DS _(Lo)≤12  (2), DS_(Lo) is 0.3 or more, the linearsaturated aliphatic acyl group is introduced in place of a hydrogen atomof a hydroxy group of the cellulose to form an ester bond, the propionylgroup is introduced in place of a hydrogen atom of a hydroxy group ofthe cellulose to form an ester bond, Izod impact strength is 5.0 kJ/m²or more, and an MFR (melt flow rate at 200° C. and under a load of 5 kg)is 10 g/10 min or more.
 2. The cellulose resin according to claim 1,wherein DS_(Lo) is in a range of 0.3 to 0.5, and DS_(Sh) is in a rangeof 1.9 to 2.3.
 3. The cellulose resin according to claim 1, wherein thelong-chain component is an acyl group moiety of at least one fatty acidselected from myristic acid, palmitic acid, stearic acid, arachidicacid, and behenic acid.
 4. The cellulose resin according to claim 1,wherein DS_(Lo)+DS_(Sh) is in a range of 2.1 to 2.6, DS_(Lo) is in arange of 0.3 to 0.5, and DS_(Sh) is in a range of 1.9 to 2.3.
 5. Thecellulose resin according to claim 4, wherein DS_(Lo)+DS_(Sh) is in therange of 2.25 to 2.6.
 6. The cellulose resin according to claim 4,wherein the DS_(Sh) is in the range 1.9 to 2.2.
 7. The cellulose resinaccording to claim 1, wherein the polymerization degree of the celluloseis in the range of 300 to
 700. 8. The cellulose resin according to claim1, wherein the MFR is 50 g/10 min or more.
 9. The cellulose resinaccording to claim 1, wherein DS_(Lo) and DS_(Sh) are obtained by NMRmeasurement with chloroform solvent.
 10. A molding material comprisingthe cellulose resin according to claim
 1. 11. A molded body formed byusing the molding material according to claim
 10. 12. A method forproducing a cellulose resin by substituting hydrogen atoms of hydroxygroups of a cellulose with a long-chain component being a linearsaturated aliphatic acyl group having 14 or more carbon atoms and ashort-chain component being an acyl group (propionyl group) having 3carbon atoms, wherein, in the cellulose resin a degree of substitutionwith the long-chain component (DS_(Lo)) and a degree of substitutionwith the short-chain component (DS_(Sh)) satisfy the followingconditional expressions (1) and (2):2.1≤DS _(Lo) +DS _(Sh)≤2.6  (1),4≤DS _(Sh) /DS _(Lo)≤12  (2), DS_(Lo) is 0.3 or more, the linearsaturated aliphatic acyl group is introduced in place of a hydrogen atomof a hydroxy group of the cellulose to form an ester bond, the propionylgroup is introduced in place of a hydrogen atom of a hydroxy group ofthe cellulose to form an ester bond, Izod impact strength is 5.0 kJ/m²or more, and an MFR (melt flow rate at 200° C. and under a load of 5 kg)is 10 g/10 min or more; and the method comprises: acylating hydroxygroups of a cellulose constituting a pulp by reacting the pulp having apolymerization degree of 300 to 700 and dispersed in a solvent withpropionyl chloride, and a long-chain reactant being an acid chloride ofa long-chain fatty acid and comprising the long-chain component, in thepresence of the acid trapping component and under warming, therebyforming an acylated cellulose being the cellulose resin formed bysubstituting hydrogen atoms of hydroxy groups of a cellulose with thelong-chain component and the short-chain component; and separating theacylated cellulose obtained in the acylating from the solvent, whereinthe solvent is selected from the group consisting of water, acetic acid,dioxane, pyridine, N-methyl pyrrolidone, N,N-dimethyl acetamide,N,N-dimethylformamide and dimethylsulfoxide, and the acid trappingcomponent is selected from the group consisting of an alkaline metalhydroxide, an alkaline earth metal hydroxide, a metal alkoxide, and anitrogen-containing nucleophilic compound.
 13. The method for producingthe cellulose resin according to claim 12, wherein the solvent is asolvent providing a liquid holding rate by the cellulose of 90% byvolume or more.
 14. The method for producing the cellulose resinaccording to claim 12, wherein the acid trapping component comprisestriethylamine or pyridine.
 15. The method for producing the celluloseresin according to claim 12, wherein an amount of the solvent is 10 to50 times as large as the dry mass of the pulp.
 16. The method forproducing the cellulose resin according to claim 12, wherein the solventis at least one selected from water, acetic acid, dioxane, pyridine,N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, anddimethyl sulfoxide.
 17. The method for producing the cellulose resinaccording to claim 12, wherein the acid trapping component comprises anitrogen-containing nucleophilic compound.
 18. The method for producingthe cellulose resin according to claim 12, wherein a nitrogen-containingnucleophilic compound is used as the acid trapping component and thesolvent.
 19. The method for producing the cellulose resin according toclaim 12, wherein the acid trapping component comprises pyridine. 20.The method for producing a cellulose resin according to claim 12,wherein the acid chloride of the long-chain fatty acid is at least oneselected from the acid chloride of myristic acid, the acid chloride ofpalmitic acid, the acid chloride of stearic acid, the acid chloride ofarachidic acid, and the acid chloride of behenic acid.
 21. The methodfor producing a cellulose resin according to claim 12, wherein anaddition amount of the acid trapping component relative to the totalamount of the long-chain reactant and the propionyl chloride is 0.1 to10 equivalents.
 22. The method for producing a cellulose resin accordingto claim 12, wherein the acid trapping component and the solvent arepyridine.
 23. The method for producing a cellulose resin according toclaim 12, wherein a reaction temperature in the acylating is 50 to 100°C.
 24. The method for producing a cellulose resin according to claim 12,wherein DS_(Lo)+DS_(Sh) is in a range of 2.1 to 2.6, and DS_(Lo) is 0.3or more.
 25. The method for producing a cellulose resin according toclaim 12, wherein the MFR is 50 g/10 min or more.
 26. The method forproducing a cellulose resin according to claim 12, wherein DS_(Lo) andDS_(Sh) are obtained by NMR measurement with chloroform solvent.